System and method for providing character interactive input/output

ABSTRACT

A system and method for supporting character interactive input/output operation in a half-duplex block-mode environment including a workstation and a server. Keystrokes at the workstation received into an auto enter, non-display entity on the workstation display are automatically transferred as entered from the workstation to a server application which processes the keystroke and responds in a manner appropriate to the context of the application.

BACKGROUND OF THE INVENTION

1. Technical Field of the Invention

This invention pertains to inter operability among various computerplatform architectures existing in a network. More particularly, itpertains to providing the look and feel of character interactive I/Ooperation across disparate architectures.

2. Background Art

In a client/server computer network, inter operability among the variousplatform architectures that exist in the network is a primary goal ofthe network. In particular, client/server network applications such asTelnet, SMTP, FTP, LPD, etc. are expected to be able to workequivalently, independent of the platform architecture on which they areimplemented. However, due to differing architectures of the variousplatforms, there are often obstacles that severely limit developing andproviding a common “look and feel” in terms of network application userinterfaces presented on each platform. One such architecture example isthe half-duplex block-mode display devices supported by the IBM 5250architecture iSeries (AS/400) and 3270 (S/390) platforms. Anotherarchitecture example is the character interactive I/O architecture, suchas supported by Unix (including AIX, Linux, etc.)

There is a need in the art for a system and method for providing thesame “look and feel” of network applications on each platform, eventhough they must be supported differently by the architectures. Thephysical rendering of the client user interface can often limit thelogical requirement of the server application in the network.

For example, when using Telnet from a Unix platform to communicate withan iSeries platform, it is expected that using Telnet from the iSeriesplatform to the Unix platform (the reverse direction) will work in anequivalent manner and have similar “look and feel” at the userinterface. Failure to work in such a bi-directional manner is an interoperability problem. Failure to inter operate creates significant userdissatisfaction due either to loss of functionality or the need to learncustom circumventions or workarounds. Worse, lack of inter operabilityleads to inability to market or sell a product as a solution in aclient/server computer network.

One such networking inter operability problem exists between the iSeriesand the Unix platforms. The iSeries is a half-duplex block-mode displaydevice architecture, which is characteristic of all 5250 and 3270 baseddisplay devices and any clone implementation. The Unix box is acharacter interactive echo-plexed architecture. Unix based displaysessions are based on VTxxx type terminals and define a standardcharacter interactive I/O keyboard as the default that must be supportedby any display clients wishing to run traditional text display basedUnix applications. In the Telnet protocol, a client host rendering adisplay should emulate the VTxxx (i.e. VT100, VT220) based display andkeyboard characteristics to the best of its ability. Due to the IBM5250/3270 display device architecture of half-duplex block-modebuffering, characters are collected in a buffer until an actionidentifier (AID) key is entered (such as Enter, program functionPF1–PF24 keystrokes, etc.) and all the keystrokes in the buffertransferred to the iSeries application, rather than processed one at atime by an application. This conflicts with the need for a VTxxx typeterminal to do character interactive I/O, which essentially means itneeds to process each character, as it is typed. This means eachcharacter keystroke typed in a half duplex block mode (iSeries Telnet)client session that is running a character interactive I/O applicationon a Unix server does not necessarily get processed within the contextof the server application as a VTxxx keystroke. Instead, it is bufferedin the iSeries display device until an action keystroke is pressed. Theaction keystroke required is normally an enter or program function (PF)key. This is a character interactive I/O inter operability problem onthe Telnet client side.

An example of a character interactive I/O inter operability probleminvolves password fields. In a native character interactive ASCIIenvironment when the client connects to a Unix Telnet server, the useris presented with a login (or sign-on) panel in which to enter theprofile or userid name and password. Typically, each character of theprofile or userid name is echoed to the screen as it is typed in, andthe cursor position moves with each character typed in. However, eachcharacter of the password is hidden by the application itself, whichechos a replacement character or characters, such as an asterisk “*”,blanks, XXX, etc. . . , or by not echoing a character at all and leavingthe cursor position unchanged. Unfortunately, again due to half-duplexblock-mode architecture design, character substitution does notautomatically occur for an iSeries Telnet client. The current iSeriesTelnet client circumvention requires the user to press the programfunction key assigned to the special function “hide keystroke echoesuntil the next action key”, which is set to PF6 by default for iSeriesTelnet client. This local “hotkey function” signals the iSeries Telnetclient program that the characters that follow are to be hidden. TheiSeries Telnet client refreshes the screen input fields with non displayattributes therein instructing the display device to simply send in thekeystrokes with the next action key (AID) to avoid displaying thekeystrokes to the screen. This also has the side effect of defeating theability of the application to substitute any preferred different “echo”characters, such as echoing a “XXX”, or “**” or “??” string for eachcharacter typed (something Lotus Notes does). Again, this solution israther “ugly” from a customer perspective, requires knowledge of thecircumvention and is not intuitive.

Another example of a character interactive I/O inter operability problemrelates to the use of graphical characters in different contexts.Consider a Lotus 1-2-3 spreadsheet application to work with saved 1-2-3files. Lotus 1-2-3 has a classic menu hotkey, where the spreadsheetapplication recognizes the “/” as a special version of the introducercharacter. In the context of the Lotus 1-2-3 application, the “/”character is to be used as a command to pop up an application selectionmenu, not as a direct character to be echoed to the display or typedinto the spreadsheet itself. In order to send the “/” alone as a “real”ASCII client would, the iSeries has to use the PF11 (“send withoutcarriage return”) trick to cause a client Telnet to avoid sending theEnter keystroke equivalent for ASCII carriage return (0x0D).

These examples are deviations from VTxxx defacto standards required byusers of 5250/3270 architectures, and it forces users to memorize customworkarounds that are generally not well-known to the average characterinteractive I/O network user. These workarounds and circumventions arenot well received by customers when 5250/3270 platforms are marketed asa solution in any network with character interactive I/O operatingsystems, and ironically do not inter operate with AIX (a RISC platform).

Referring to FIG. 1, full duplex operation is illustrated. VTxxx isfull-duplex character interactive mode support. This means that as eachcharacter is typed on the client workstation, it is sent to the Unixserver for processing. The Unix server application then decides based onthe content of the dialogue whether to echo the character to the clientworkstation so that it appears on the display terminal. Thus, in nativeVTxxx based display, each character typed makes a full round-trip pathfrom the client workstation to the Unix server and back to the clientworkstation for display. As is represented by lines 24 and 25,keystrokes entered at keyboard 20 are sent directly by clientworkstation 22 to character interactive application 23. As isrepresented by lines 26 and 27, character interactive I/O applicationoutput is returned directly to display 21. The round trip 24, 25, 26 and27 may occur (again the application may choose to not echo or advancethe cursor) for each keystroke, that is for every character input atkeyboard 20.

Referring to FIG. 2, half duplex operation is illustrated, such as wouldbe implemented in an iSeries (5250) configuration. In thisconfiguration, keystrokes 24 entered at keyboard 20 are accumulated inbuffer 30. If local echoing is on (normally, echoing is on by default),as is represented by element 35, these keystrokes 24 will be echoedlocally to display 21 (as it is typed on the keyboard 20). As isrepresented by element 33, when an enter action key is detected inbuffer 30 from keystrokes 24, buffered data is sent to application 32for processing. Application output 34, 36 is sent to client display 21.The round trip represented by elements 24, 30, 33, 34 and 36 occurs whenan action key is depressed at keyboard 20 and detected by clientworkstation 31.

The above discussion of half duplex (see FIG. 2) is oversimplified inthat there is no visible TCP/IP network in the figure. While such aconfiguration may exist in hardwired networks that use dumb terminalsconnected via Twinax cabling, the trend in current technology is towarda TCP/IP, or the like, network. (The present invention applies to anyclient including SNA or Twinax and is not limited to TCP.)

Referring to FIG. 3, in a TCP/IP network, dumb terminals are replacedwith terminal emulators that run on PC workstations and are essentiallyTelnet clients. This emulator configuration operates in cascaded halfduplex mode, a half duplex block-mode imitation of character interactiveI/O. Most iSeries customers connect to the iSeries in a TCP/IP networkusing a Telnet client 40 bundled as part of a package. Client AccessExpress is an example of such a package. In such a configuration,connectivity for the iSeries from the client workstation 31 using halfduplex block mode is achieved without any keystroke problems forapplications written with half-duplex block mode architecture andrunning on the iSeries 43. The problem with half duplex block modearises when that same client 31, which is already connected to theiSeries 43, then tries to connect to a Unix platform 48 using theiSeries Telnet client 45 and run applications 49 on the Unix platform.That is, workstation 31 uses a terminal emulator (e.g., Client AccessExpress) to connect to iSeries 45 via Telnet server 43 and gets acommand line 44. At command line 44, Telnet client 45 is used to cascadeto Unix Telnet server 48 and run application 49. Application 49 needsVTxxx mode (full duplex character mode represented by lines 46, 47) towork properly with keyboard 20 and display 21, but block-mode operationof workstation 31 interferes.

Illustrated in FIG. 2 is the operation of a 5250/3270 configuration,which requires that all data be in EBCDIC format. Illustrated in FIG. 3is a Unix platform, which requires that the EBCDIC be converted atelement 39 to ASCII by the iSeries Telnet client before it is put on thecommunication link to the Unix box 48. Thus, ASCII data goes out on line46 and returns on line 47 to client 45. Not only is data translated inconverter 39, but action keys in EBCDIC such as the enter (0xF1) key areconverted into equivalent ASCII control codes.

There is a need in the art for a system and method which solves thecharacter interactive I/O inter operability problem on the iSeriesTelnet client.

It is, therefore, an object of the invention to provide an improvedsystem and method for rendering a common “look and feel” on differentplatforms and architectures.

It is a further object of the invention to provide a system and methodfor character interactive I/O in a half duplex block mode environment.

SUMMARY OF THE INVENTION

A system and method for supporting character interactive input/outputoperation in a half-duplex block-mode environment including aworkstation and a server. Keystrokes at the workstation received into anauto enter, non-display entity on the workstation display areautomatically transferred as entered from the workstation to a serverapplication which processes the keystroke and responds in a mannerappropriate to the context of the application.

Other features and advantages of this invention will become apparentfrom the following detailed description of the presently preferredembodiment of the invention, taken in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates full duplex character mode in accordance with theprior art VTxxx architecture.

FIG. 2 illustrates half duplex block mode in accordance with the priorart 5250/3270 architecture.

FIG. 3 illustrates half duplex block mode in combination with fullduplex character mode, and illustrates the problem configuration of theprior art addressed by the present invention.

FIG. 4 illustrates a preferred embodiment of the invention, including anauto enter non-display character position on a local display forreceiving all keyboard entered data.

FIG. 5 illustrates a preferred embodiment of the invention, including anetwork connection between the workstation and Telnet client.

FIG. 6 illustrates the four layers of the TCP/IP protocol suite.

BEST MODE FOR CARRYING OUT THE INVENTION

In accordance with the preferred embodiment of the invention, an autoenter non-display character position on a local display is used toreceive text based keystrokes from the keyboard.

In an exemplary embodiment, in a half-duplex block-mode device, such asa 5250 display device, buffering of typed characters, in the sense ofblock-mode buffering done by the 5250/3270 architecture, is avoided andeach character as typed is translated from EBCDIC to ASCII and thenforwarded in a manner like that of a native character interactive I/Onetwork client.

Several acronyms are used herein, including the following:

FTP file transfer protocol IPX Internet packet exchange LPD line printerdaemon (a daemon is a server, which is a listening job or process.) LUDlogical unit descriptor RISC reduced instruction set computing SMTPsimple mail transport protocol SNA system network architecture VT100character interactive mode

VT100 is a Digital Equipment Corporation (DEC) model that has become thede facto standard for text based display mode.

Referring to FIG. 4, 5250 display device 52 is configured or defined(with respect to keyboard 50) as comprising a 1-byte character inputfield 53 that has auto-enter and non-displayable attributes, asdistinguished from the normal 1920-byte character input field that ispossible on a 24×80 display device. The auto-enter attribute acts likean internal windows based visibility (scan codes, etc . . . ) andaffords the emulator the ability to send an action key (AID) in thiscontext, since it causes an attention signal 79 to the workstationrunning Client Access Express 55 to occur. This attention signal 79 isthen passed to the iSeries Telnet Client 77 via the iSeries TelnetServer 78 as represented by line 57B. The non-displayable attributeprevents any local echo from showing an input character on the display.

As characters 51 are typed at workstation keyboard 50, an attentionidentifier (AID) 79 is signaled from the workstation (running ClientAccess Express) 55, to the iSeries Telnet client 77 via the iSeriesTelnet server 78 as represented by line 57B, and a 1-byte characterinput field content is retrieved from a keystroke buffer 53 and sent, asis represented by line 56, workstation (running Client Access Express)55 and passed on to iSeries Telnet client 77 via the iSeries Telnetserver 78 as represented by line 57 b. ISeries Telnet client 77 thentranslates the character from EBCDIC to ASCII and safely transmits thekeystroke, as is represented by line 57A, to remote Unix application 58via Unix Telnet Server 58B, where the keystroke is interpreted withinthe context of the Unix application 58. As is represented by line 59A,the output (if any) of Unix application is then returned to the iSeriesTelnet client 77 and passed on to workstation (running Client AccessExpress) 55 via the iSeries Telnet server 78 and, as represented by line60, to workstation display 52 (which is “business as usual”).

Thus, by configuring display device 52 to a 1-byte field 53, processingoccurs immediately for each character 51 typed at keyboard 50, asopposed to buffering many keystrokes while waiting for action or AIDkey.

In accordance with this embodiment of the invention, a user typing apassword, for example, for a character interactive I/O application 58would see, in password display field 54 of display 52, the effect ofapplication 58 hiding each keystroke of the password and, as shown inFIG. 4, echoing back another character, in this example the “*”character, instead of seeing the password echoed to field 54 of display52 as would typically occur for 5250 block-mode devices. This removesthe need to use circumventions, such as the PF6 “hide keystroke echoesuntil the next action key” work around previously described.

This significantly enhances the iSeries's heterogeneous connectivity tomore seamlessly connect with character interactive I/O dependentoperating systems such as Unix.

Referring to FIG. 5, the embodiment of the invention shown in FIG. 4 isfurther described, illustrating a typical network environment.

A user terminal 62 including keyboard 50 and display 52, is connectedthrough network 69A to iSeries Telnet server 78 and iSeries Telnetclient 77 and ultimately via network 69B to server application 74 andhost application 76. This is done via protocol stacks for workstation84, 5250/3270 platform 100, and Unix box 84. These protocol stacksinclude a plurality of layers 64–67, 101–103, and 71–74, respectively,in, for example, a TCP/IP protocol suite (as further described inconnection with FIG. 6). In this example, terminal emulator 67 is aTelnet client, such as Client Access Express.

Referring to FIG. 6, the four layers 80–83 of the TCP/IP protocol suiteinclude application layer 83, such as Telnet or FTP 98, transport layer82, such as TCP 97, network layer 81, such as IP 96, and link layer 80,such as device driver or network cards 95. Through the technique ofencapsulation, direct communication between protocol stacks occurs onlybetween equivalent layers. For example, referring to FIG. 5, link layer66 communicates with link layer 71, network layer 65 communicates withnetwork layer 72, transport layer 64 communicates with transport layer73, and application layer 67 communicates with application layer 74.

In accordance with a further embodiment of the invention, workstation84, iSeries Telnet server 78 and iSeries Telnet client 77 connecting toUNIX server 85 together represent a cascaded connection, which is asequence of connections from the users local workstation to the finalremote server on which the application is running, requiring characterdependent input/output in full duplex mode.

ADVANTAGES OVER THE PRIOR ART

It is an advantage of the invention that there is provided an improvedsystem and method for rendering a common “look and feel” on differentplatforms and architectures.

It is a further advantage of the invention that there is provided animproved system and method for character interactive I/O in a halfduplex block mode environment.

ALTERNATIVE EMBODIMENTS

It will be appreciated that, although specific embodiments of theinvention have been described herein for purposes of illustration,various modifications may be made without departing from the spirit andscope of the invention. In particular, it is within the scope of theinvention to provide a computer program product or program element, or aprogram storage or memory device such as a solid or fluid transmissionmedium, magnetic or optical wire, tape or disc, or the like, for storingsignals readable by a machine, for controlling the operation of acomputer according to the method of the invention and/or to structureits components in accordance with the system of the invention.

Further, each step of the method may be executed on any generalcomputer, such as an IBM System 390 (z Series), AS/400 (i Series), PC (xSeries), RISC/6000 (p Series), or the like and pursuant to one or more,or a part of one or more, program elements, modules or objects generatedfrom any programming language, such as C++, Java, P1/1, Fortran or thelike. And still further, each said step, or a file or object or the likeimplementing each said step, may be executed by special purpose hardwareor a circuit module designed for that purpose.

While the exemplary embodiments of the invention have been describedprimarily with respect a preferred client server application of Telnetand thus to a TCP/IP environment, the invention is not limited to such.IPX and SNA network transports can also benefit for use of theinvention. Also, when reference is made to the Unix architecture,several flavors of Unix are contemplated, including AIX, Linux, Sun, andso forth. RISC and Sun Solaris computers are most often associated withUnix architecture, the iSeries computer is most often associated with5250 architecture, and S/390 computers (such as those running theVirtual Machine (VM) operating system) most often associated with 3270architecture. All these computer architectures can support the variousnetwork transports (TCP/IP, IPX, SNA, et.) and therefore this inventioncan apply to the many variations and permutations of each possiblenetwork configuration.

The invention is not even limited to networking environments since aTwinax display with standard 5250 architectural support of theauto-enter feature can be programmed to exploit this invention,affording the character interactive I/O.

Accordingly, the scope of protection of this invention is limited onlyby the following claims and their equivalents.

1. A method for executing full character interactive input/output modecommunication at the application level of a TCP/IP protocol stack in ahalf duplex block mode environment requiring a half duplex block modeinterface between a client workstation and a server, comprising thesteps of: operating said client to communicate in said application levelover said half duplex block mode interface with a first serverapplication written with half-duplex block mode architecture inhalf-duplex block mode; operating said client to communicate over saidhalf duplex block mode interface with a second server applicationrequiring full duplex character interactive mode by: receiving a keystroke into a buffer at said client workstation; automaticallytransferring said keystroke from said client workstation over a halfduplex block mode interface to a full duplex character interactiveinput/output server application; and said full duplex characterinteractive input/output server application processing said keystrokeand responding appropriate to context of said full duplex characterinteractive server application; thereby transferring single key strokesas they are entered at said client workstation even though operating insaid half duplex block mode environment in which character sequences arenormally transferred.
 2. The method of claim 1, said buffer being anauto enter, non-display entity on a display screen.
 3. The method ofclaim 1, said buffer being a non-screen entity accessible to said clientworkstation.
 4. A method for character interactive input/output in ahalf duplex block mode environment, comprising the steps of: connectinga client to a first server application written to half-duplex block modearchitecture; operating said client to communicate over a half duplexblock mode interface to said first server application in half-duplexblock mode; connecting said client to a second server applicationwritten to full duplex character interactive mode architecture;operating said client to communicate over said half duplex block modeinterface with said second server application in full duplex characterinteractive mode by: configuring a workstation display device at aclient workstation to a one character field; and immediately upon entryof an input character into said one character field, processing saidinput character by signaling an attention identifier from a clientemulator application, and responsive to said attention identifier,retrieving said input character from said one character field; therebytransferring single key strokes as they are entered at said onecharacter field even though operating in said half duplex block modeenvironment in which character sequences are normally transferred. 5.The method of claim 4, further comprising the step of translating andcommunicating said input character to a remote server and applicationfor interpretation within the context of said remote application.
 6. Themethod of claim 5, further comprising the step of returning from saidremote application to said client workstation a display character fordisplay at said workstation display device.
 7. The method of claim 6,said display character selectively comprising an echo character whichmay be said input character.
 8. A method for operating a clientapplication in character interactive input/output mode in a half duplexblock mode environment, comprising the steps of: connecting said clientapplication to a first server application written to half-duplex blockmode architecture; operating said client application to communicate overa half duplex block mode interface to said first server application inhalf-duplex block mode; connecting said client application to a secondserver application written to full duplex character interactive modearchitecture; operating said client application to communicate over saidhalf duplex block mode interface with said second server application infull duplex character interactive mode by: responsive to receiving anattention command from a keyboard, retrieving from a one characterdisplay buffer configured as an auto-entry non-displayable display asingle input character; and translating and communicating said inputcharacter to a remote application for interpretation within the contextof said remote application; thereby transferring single key strokes asthey are entered at said keyboard even though operating in said halfduplex block mode environment in which character sequences are normallytransferred.
 9. A method for operating a display operating in a halfduplex block mode environment, comprising the steps of: connecting aclient application to a first server application written to half-duplexblock mode architecture; operating said client application tocommunicate over a half duplex block mode interface to said first serverapplication in half-duplex block mode; connecting said clientapplication to a second server application written to full duplexcharacter interactive mode architecture; operating said clientapplication to communicate over said half duplex block mode interfacewith said second server application in full duplex character interactivemode by: configuring said display with respect to a character entrydevice as a one character, auto-entry, non-displayable buffer;responsive to entry of an input character into said one character,auto-entry, non-displayable buffer, immediately communicating said inputcharacter to a remote application for interpretation; therebytransferring single key strokes as they are entered at said onecharacter, auto-entry, non-displayable buffer even though operating insaid half duplex block mode environment in which character sequences arenormally transferred.
 10. The method of claim 9, further comprising thesteps of: receiving from said remote application an echo characterselectively not said input character; and displaying said echocharacter.
 11. A system including a workstation and a server forcharacter interactive input/output in a half duplex block modeenvironment, comprising: a network for connecting said workstation tosaid server; said workstation including a client application; a firstserver application written to half-duplex block mode architecture; saidclient application for communicating over a half duplex block modeinterface to said first server application in half-duplex block mode; asecond server application written to full duplex character interactivemode architecture; said client application for communicating over saidhalf duplex block mode interface with said second server application infull duplex character interactive mode including: a workstation displayconfigured as a 1-byte character input field that has auto-enter andnon-displayable attributes; a keyboard for entering a keystroke intosaid input field; said workstation automatically transferring each saidkeystroke from said workstation display to a server application; andsaid server application for processing said keystroke and responding tosaid workstation with an echo character appropriate to context of saidserver application for display at said workstation display; therebytransferring single key strokes as they are entered at said workstationeven though operating in said half duplex block mode environment inwhich character sequences are normally transferred.
 12. A programstorage device readable by a machine, tangibly embodying a program ofinstructions executable by a machine to perform method steps forcharacter interactive input/output in a half duplex block modeenvironment including a workstation and a server, said method stepscomprising: operating said workstation to communicate a half duplexblock mode interface with a first server application written withhalf-duplex block mode architecture in half-duplex block mode; operatingsaid workstation to communicate over said half duplex block modeinterface with a second server application requiring full duplexcharacter interactive mode by: receiving a key stroke into a buffer atsaid workstation; automatically transferring said key stroke from saidworkstation to a server application; said server application processingsaid keystroke and responding appropriate to context of said serverapplication; thereby transferring single key strokes as they are enteredat said buffer even though operating in said half duplex block modeenvironment in which character sequences are normally transferred.
 13. Aprogram storage device readable by a machine, tangibly embodying aprogram of instructions executable by a machine to perform method stepsfor character interactive input/output in a half duplex block modeenvironment including a workstation and a server, said method stepscomprising: connecting said client workstation to said server over ahalf duplex block mode interface; communicating with said server oversaid half duplex block mode interface selectively according to halfduplex block mode and full duplex character interactive input/outputmode; when communicating with said server in said full duplex characterinteractive input/output mode, defining a workstation display as a1-byte character input field that has auto-enter and non-displayableattributes; receiving a keystroke into said input field; automaticallytransferring said keystroke from said workstation display to a serverapplication; said server application processing said keystroke andresponding appropriate to context of said server application; therebytransferring single key strokes as they are entered at said clientworkstation even though operating in said half duplex block modeenvironment in which character sequences are normally transferred.
 14. Aprogram storage device readable by a machine, tangibly embodying aprogram of instructions executable by a machine to perform method stepsfor character interactive input/output in a half duplex block modeenvironment, said method steps comprising the steps of: operating aclient to communicate over a half duplex block mode interface with afirst server application written with half-duplex block modearchitecture in half-duplex block mode; operating said client tocommunicate over said half duplex block mode interface with a secondserver application requiring full duplex character interactive mode by:configuring a workstation display device to a one character field; andimmediately upon entry of an input character into said one characterfield, processing said input character by signaling an attentionidentifier to a client emulator application, and responsive to saidattention identifier, retrieving said input character from said onecharacter field; thereby transferring single input characters as theyare entered at said one character field even though operating in saidhalf duplex block mode environment in which character sequences arenormally transferred.
 15. A program storage device readable by amachine, tangibly embodying a program of instructions executable by amachine to perform method steps for operating a client application incharacter interactive input/output mode in a half duplex block modeenvironment, said method steps comprising the steps of: operating saidclient application to communicate over a half duplex block modeinterface with a first server application written with half-duplex blockmode architecture in half-duplex block mode; operating said client tocommunicate over said half duplex block mode interface with a secondserver application requiring full duplex character interactive mode by:responsive to receiving an attention command from a keyboard, retrievingfrom a one character display buffer configured as an auto-entrynon-displayable display a single input character; and translating ancommunicating said input character to a remote application forinterpretation within the context of said remote application; therebytransferring single key strokes as they are entered at said keyboardeven though operating in said half duplex block mode environment inwhich character sequences are normally transferred.
 16. The method ofclaim 1, said automatically transferring step further comprising thesteps of: transferring said key stroke from said client workstation to aTelnet client and thence to said full duplex character interactive (I/O)server application via a Unix server.